This project grew out of our neurophysiological and neuroanatomical investigation of the corticocortical connections in the somatic sensorimotor cortex of monkeys and their role in the control of primate motor behavior. In that project we redefined three of the main cortical inputs to the primary motor cortex (MI): the premotor cortex (PM), the supplementary motor cortex (MII) and the transition zone between the motor and somatic sensory cortex, area 3a. These three cortical fields surround MI and can be differentiated from MI on the basis of neuronal responses to peripheral inputs, thresholds for evoking movements with intracortical electrical stimulation, the properties of single neurons during the performance of an operantly conditioned motor task, cytoarchitecture, and connectivity. We then elaborated this study by an analysis of the activity of single neurons in PM during a variety of visually guided motor tasks. Each of these behavioral tasks was designed to elucidate the role of PM in the cerebral control of movement. We have tested the following hypotheses: that PM guides movement to points in space, that PM is involved in the sensory guidance of movement, that PM plays a role in motor preparation that it functions in the determination of movement parameters, that it reflects eye position, gaze position, postural muscle activity, visual fixation, attention, motivation, or arousal. Of these ideas, our results support the hypothesis that PM plays a role in the execution of visually guided movements and the preparation for voluntary movements.